CHAPTER 58 • KNEE MENISCAL INJURIES 349- The technique of allograft transplantation has proved
to be reproducible in terms of healing, and control of
postmeniscectomy pain and swelling. The exact indi-
cations for allograft transplantation, however, con-
tinue to be developed (Rodeo, 2001). When properly
indicated, transplant leads to predictable good results
in over 90% of patients (Klimkiewicz and Shaffer,
2002). - Meniscal allograft transplantation may be considered
for patients with symptoms referable to a meniscus-
deficient tibiofemoral compartment. These symptoms
include pain and swelling, more commonly than
mechanical symptoms (Klimkiewicz and Shaffer,
2002; Rodeo, 2001). - It is not possible, at this time, to identify patients that
will develop symptomatic arthrosis after meniscec-
tomy, and therefore prophylactic transplantation in the
asymptomatic patient after meniscectomy has not
been justified (Klimkiewicz and Shaffer, 2002).
•Ideally, an objective marker of early pathologic
changes to articular surfaces will be identified to
allow identification of appropriate patients for
early meniscus replacement. Such markers may be
found through advanced imaging techniques, or
synovial fluid analysis for cartilage degradation
products.
•Transplantation results are poor in cases of advanced
joint degeneration, and therefore should only be con-
sidered when no more than fibrillation and fissuring
of the articular surfaces is present. - Full-thickness articular cartilage lesions on the flex-
ion weight-bearing zone of the femoral condyle or
tibia greater than 10–15 mm in diameter is a con-
traindication to transplantation (Greis et al, 2002b;
Rodeo, 2001). - Additionally, in order to be a candidate for transplan-
tation, the knee must be stable, without malalignment.
An unstable knee must be stabilized, and malalign-
ment requires correction to avoid direct weight bear-
ing through the involved compartment receiving the
meniscus transplant (Klimkiewicz and Shaffer, 2002;
Rodeo, 2001).
MENISCUS SCAFFOLDS
•Bovine collagen meniscal scaffolds, termed collagen
meniscal implants (CMI), have been approved for
human implantation in Europe, Australia, and Chile.
These implants are currently under evaluation in the
United States in an ongoing multicenter trial. The
scaffold is gradually replaced by meniscus-like
tissue as fibrochondrocytes proliferate within the
scaffold.
- Preliminary trials have shown that CMI scaffolds
demonstrate promise as an alternative to allograft.
Patients note subjective improvement in symptoms,
with generation of meniscus-like tissue viewed by
arthroscopy and histology (Stone et al, 1997). - Porcine small intestine submucosa, which contains
collagen and multiple growth factors, is an alternative
scaffold under consideration and currently used in
animal trials (Welch et al, 2002).
FUTURE DIRECTIONS- Future treatments in both meniscus repair and
replacement continue to evolve.
•Several growth factors and cytokines are under inves-
tigation as potential adjuncts to potentiate healing.
•Meniscal fibrochondrocytes respond with migration
and proliferation to growth factors, including platelet
derived growth factor (PDGF), hepatocyte growth
factor(HGF), bone morphogenic protein- 2 (BMP-2),
insulin-like growth factor-1(IGF-1), and transform-
ing growth factor-beta (TGF-β) (Bhargava et al, 1999;
Ochi et al, 2001). - Suggested delivery systems for growth factors include
impregnated absorbable scaffolds, impregnated fixa-
tion devices, or even virus vectors for gene therapy
(Martinek et al, 2002).
•Tissue engineering may be the next step in develop-
ment of a durable meniscal replacement. This tech-
nique combines the technology of cell culture,
polymer chemistry, and biology to create tissues that
are appropriate for tissue replacement or reconstruc-
tion. The implant would incorporate fibrochondro-
cytes that have been multiplied in cell culture, in
appropriate shaped polymer scaffolds.
REFERENCES
Andersson-Molina H, Karlsson H, Rockborn P: Arthroscopic
partial and total meniscectomy: A long-term follow-up study
with matched controls. Arthroscopy18(2):183–189, 2002.
Arnoczky SP, McDevitt CA: The meniscus: Structure, function,
repair, and replacement, in Orthopaedic Basic Science:
Biology and Biomechanics of the Musculoskeletal System, 2nd
ed. Rosemont, IL, AAOS, 2000, pp 531–545.
Bhargava MM, Attia ET, Murrell GAC, et al: The effect of
cytokines on the proliferation and migration of bovine menis-
cal cells. Am J Sports Med 27(5):636–643, 1999.
Eggli S, Wegmueller H, Kosina J, et al: Long-term results of
arthroscopic meniscal repair. Am J Sports Med23:715–720,
1995.